1. Technical Field
The present invention relates to a reproduction method for producing multi-color printings, whereby the chromatic impression arises by means of a multitude of inked surface elements.
2. Description of the Prior Art
It is known in printing technology to produce multi-color printing with the assistance of color separations, whereby one color separation is produced for every printing ink and the reproduction is produced by means of superimposed printing of the sub-images established by the color separations. Usually, three chromatic printing inks, magenta (M), cyan (C) and yellow (Y), are employed or, respectively, the color black (S) in addition given four-color printing. This printing process is based, on the one hand, on the law of subtractive mixing and, on the other hand, on the law of optical mixing (additive mixing). As a result of the law of subtractive mixing, the secondary and tertiary colors of the various elemntal surfaces arise due to superimposed printing of glazing ink layers, whereby elemental surfaces are formed in the colors yellow, magneta-red, cyan blue, orange-red, green, violet-blue and black. The elemental surfaces in white arise by means of the paper locations not covered with printing ink. The secondary colors orange-red, green and violet-blue arise by means of superimposed printing of respectively two glazing, chromatic ink layers. Elemental surfaces in black arise by means of superimposed printing of the three chromatic ink layers. Elemental surfaces in black are added by means of the ink black.
The production of such color separations ensues by means of so-called scanners, whereby the German Letters Patent No. 21 07 738 which corresponds to U.S. Pat. No. 3,725,524, is referenced. Such apparatus have been in commercial use for some time, thus, for example, the scanner type DC 300 or the scanner Chromagraph CTX 330 of Dr.-Ing. Rudolf Hell GmbH, Kiel. The scanner Chromagraph CTX 330 is described in the publication No. 1483 (T-ld-8201) of Dr.-Ing. Rudolf Hell GmbH, Kiel, dated January 1982. which corresponds to US Edition. The versatile chromagraph CTX 330, which is available in the US from HCM Corp. Cutter Mill road; Great Neck, N.Y. 10021. Such scanners function, for example, with a laser writing unit for generating the raster points, whereby the raster point configurations are stored and the laser writing unit is controlled during recording with the assistance of these stored data.
The German OS No. 32 03 972 which corresponds to U.S. Pat. No. 4,412,225 and the German OS No. 30 37 774 which corresponds to U.S. Pat. No. 4,367,481 also specify a method for the representation of multi-color images wherein an ink application by means of an ink jet ensues such that individual elemental surfaces are inked in that ink drops are deposited in a matrix with the printing inks M,G,C,Y. Additive mixing (optical mixing) is thereby likewise employed given low tint values and subtractive mixing is employed given high tint values.
These printing methods are very widespread but are burdened with disadvantages; thus, for example, color acceptance problems occur when printing, moire appears when the screen angle is not exactly observed, and pure and luminous colors cannot be reproduced well.